The present invention relates to an orifice valve for an ultrasonic liquid atomizer as described in German Patent Application No. 3036721, published Apr. 8, 1982, incorporated herein by reference. Such an ultrasonic liquid atomizer comprises an ultrasonic oscillator with a work plate, an axial bore for liquid supply to a surface of the work plate, and an impact body which serves for the deflection and distribution of the supplied liquid on the work plate. In such a liquid atomizer the impact body has a stem which is situated in the axial bore of the oscillator under the work plate and which exhibits a centering in the bore at least in that area of the axial bore which is situated close to the discharge opening of the bore. Given this liquid atomizer, the stem of the impact body is continued by a retaining wire which is secured outside of the oscillator in a region of said oscillator lying opposite the work plate. Given such a liquid atomizer, the retaining wire extends out of the end of the oscillator opposite the impact body.
In this liquid atomizer, the stem preferably has a shape with more than two edges and, in particular, is designed with star-like cross-section, a centering of the stem in the bore being thus achieved. The head of the impact body is preferably designed mushroom-like with a convex exterior surface and its lower face facing the surface of the atomizer plate has an outer edge which has a radial dimension greater than a corresponding dimension radius of the bore in the atomizer plate.
An ultrasonic liquid atomizer (according to the aforementioned patent) as described above has proven itself for atomizing liquids, particularly volatile oils and solutions of medications, cosmetics and insecticides. In contrast to water, however, additional difficulties arise when atomizing liquids (such as cited above by way of example) when the atomization is temporarily interrupted. During the idle times, a thickening, encrustation and/or sticking of the discharge opening provided in the atomizer plate for the liquid can occur, particularly due to evaporation, depending upon the type of liquid or solvent.
A resolution of this problem could be to retract the supplied liquid upon termination of the atomization operation so that the discharge opening remains free of such a fluid during its idle time. Such a technique, however, is very involved and may not be practical, particularly given atomization of medication because foreign materials could also be trapped with the retraction into the discharge opening.